Microwave energy-delivery device and system

ABSTRACT

A microwave ablation device including a cable assembly configured to connect a microwave ablation device to an energy source and a feedline in electrical communication with the cable assembly. The microwave ablation device further includes a balun on an outer conductor of the feedline, and a temperature sensor on the balun sensing the temperature of the balun.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of U.S. patentapplication Ser. No. 13/834,581, now U.S. Pat. No. 9,119,650, filed onMar. 15, 2013 and titled “MICROWAVE ENERGY-DELIVERY DEVICE AND SYSTEM,”the entire contents of which are incorporated herein by reference.

BACKGROUND

1. Technical Field

The present disclosure relates to microwave surgical devices suitablefor use in tissue ablation applications.

2. Discussion of Related Art

Treatment of certain diseases requires the destruction of malignanttissue growths, e.g., tumors. Electromagnetic radiation can be used toheat and destroy tumor cells. Treatment may involve inserting ablationprobes into tissues where cancerous tumors have been identified. Oncethe probes are positioned, electromagnetic energy is passed through theprobes into surrounding tissue.

In the treatment of diseases such as cancer, certain types of tumorcells have been found to denature at elevated temperatures that areslightly lower than temperatures normally injurious to healthy cells.Known treatment methods, such as hyperthermia therapy, heat diseasedcells to temperatures above 41° C. while maintaining adjacent healthycells below the temperature at which irreversible cell destructionoccurs. These methods involve applying electromagnetic radiation to heator ablate tissue.

Electrosurgical devices utilizing electromagnetic radiation have beendeveloped for a variety of uses and applications. Typically, apparatusfor use in ablation procedures include a power generation source, e.g.,a microwave or radio frequency (RF) electrosurgical generator thatfunctions as an energy source and a surgical instrument (e.g., microwaveablation probe having an antenna assembly) for directing energy to thetarget tissue. The generator and surgical instrument are typicallyoperatively coupled by a cable assembly having a plurality of conductorsfor transmitting energy from the generator to the instrument, and forcommunicating control, feedback and identification signals between theinstrument and the generator.

There are several types of microwave probes in use, e.g., monopole,dipole and helical, which may be used in tissue ablation applications.In monopole and dipole antenna assemblies, microwave energy generallyradiates perpendicularly away from the axis of the conductor. Monopoleantenna assemblies typically include a single, elongated conductor. Atypical dipole antenna assembly includes two elongated conductors thatare linearly-aligned and positioned end-to-end relative to one anotherwith an electrical insulator placed therebetween. Helical antennaassemblies include helically-shaped conductor configurations of variousdimensions, e.g., diameter and length. The main modes of operation of ahelical antenna assembly are normal mode (broadside), in which the fieldradiated by the helix is maximum in a perpendicular plane to the helixaxis, and axial mode (end fire), in which maximum radiation is along thehelix axis.

The particular type of tissue ablation procedure may dictate aparticular ablation volume in order to achieve a desired surgicaloutcome. Ablation volume is correlated with antenna design, antennaperformance, antenna impedance, ablation time and wattage, and tissuecharacteristics, e.g., tissue impedance.

Because of the small temperature difference between the temperaturerequired for denaturing malignant cells and the temperature normallyinjurious to healthy cells, a known heating pattern and precisetemperature control is needed to lead to more predictable temperaturedistribution to eradicate the tumor cells while minimizing the damage tootherwise healthy tissue surrounding the tissue to which electrosurgicalenergy is being applied. Fluid-cooled or dielectrically-bufferedmicrowave devices may be used in ablation procedures. During operationof the microwave ablation device, if the flow of coolant or bufferingfluid is interrupted, the microwave ablation device may exhibit rapidfailures due to the heat generated from the increased reflected power.

SUMMARY

According to an aspect of the present disclosure, an energy-deliverydevice suitable for delivery of energy to tissue is provided. The energydevice may be a microwave ablation device including a cable assemblyconfigured to connect a microwave ablation device to an energy sourceand a feedline in electrical communication with the cable assembly. Themicrowave ablation device also includes a balun on an outer conductor ofthe feedline and a temperature sensor disposed on the balun and sensingthe temperature of the balun. The balun may include a balun shortelectrically connecting the balun to the outer conductor and adielectric material in contact with the balun short. The temperaturesensor may be in physical contact with the balun short.

According to another aspect of the present disclosure the balun shortand dielectric material are held in place on the feedline by a heatshrink material and may further include an electrically conducting inkdisposed between the heat shrink material and the balun. The temperaturesensor may be held in contact with the balun short by the heat shrinkmaterial and a wire of the temperature sensor is secured to the feedlineby a second heat shrink material. Further, a portion of the dielectricmaterial may extend distally beyond the distal most portion of the heatshrink material.

According to another aspect of the present disclosure the microwaveablation device includes an inner tubular member and an outer tubularmember, and the feedline, inner tubular member, and outer tubularmembers are arranged columinally. The microwave ablation device furtherincludes a distal radiating section connected to the feedline, a portionof which extends beyond the inner tubular member. Further, gaps betweenthe feedline and the inner tubular member and between the inner tubularmember and the outer tubular member to enable fluid flow through theablation device.

According to a further aspect of the present disclosure a proximal endof the inner tubular member connects to a fluid outflow port and theproximal end of the outer tubular member connects to a fluid inflowport, fluid flow through the ablation device providing cooling whenenergized. The microwave ablation device further includes a hub having afirst chamber in fluid communication with the fluid inflow port and asecond chamber in fluid communication with the fluid outflow port. Thefirst and second chambers may be separated by a hub divider, and theinner tubular member may be secured in the hub by the hub divider. Thehub divider may be formed of an elastic material and include asubstantially rigid metal ring securing the hub divider to the proximalportion of the inner tubular member, the proximal portion having agreater diameter than a distal portion of the inner tubular member.Still further the hub, the inner and outer tubular members, thefeedline, and the transition are secured within a handle body, theiralignment being maintained by one or more alignment pins.

A further aspect of the present disclosure is directed to a microwaveablation device including a handle assembly fluidly enclosing a portionof a microwave feedline and a cooling assembly and a tubular memberextending from the handle assembly and enclosing a distal portion of thefeedline and the cooling assembly. The distal portion of the feed lineterminates in a radiating section and the distal portion of the coolingassembly is configured to cool the radiating section. The microwaveablation device also includes a flexible cable assembly connected to thehandle assembly and enclosing a proximal portion of the feedline, theflexible cable assembly configured to connect the feedline to an energysource, and a temperature sensing system associated with the cableassembly and configured to sense a temperature profile of tissuesurrounding the distal radiating end of the tubular member.

The microwave ablation device includes at least one temperature sensorwhich may be located on the distal portion of the feedline sensing thetemperature of the distal portion of the feedline. The microwaveablation device may also include a temperature sensor on the tubularmember sensing the temperature of tissue adjacent the tubular member.

One aspect of the present disclosure is a microwave ablation deviceincluding a plurality of temperature sensors located at points along thetubular member sensing the temperature of tissue adjacent the tubularmember. The temperature sensing system may receive temperature data fromeach of the temperature sensors, and the temperature data providesfeedback to the energy source to control the operation of the energysource. The temperature sensing system may compare the receivedtemperature data to temperature profiles stored in a memory fordetermining whether sufficient energy has been applied to the tissue.

According to further aspects of the present disclosure the temperaturesensing system stores in the memory radiation patterns associated withthe received temperature data, a duration of energy application, and apower setting of the energy source. Further the energy source may ceaseapplication of energy when one of the sensed temperatures exceeds athreshold. The temperature sensors may detect the temperature of acooling fluid in the cooling assembly or the temperature of tissuesurrounding the tubular member.

BRIEF DESCRIPTION OF THE DRAWINGS

Objects and features of the presently disclosed energy-delivery deviceswith a fluid-cooled probe assembly and systems including the same willbecome apparent to those of ordinary skill in the art when descriptionsof various embodiments thereof are read with reference to theaccompanying drawings, of which:

FIG. 1 is an exploded view of a medical device in accordance with anembodiment of the present disclosure;

FIG. 2A is a schematic diagram of a medical device including a probe, ahub assembly, and a generator connector assembly in accordance with anembodiment of the present disclosure;

FIG. 2B is cross-sectional view of the coaxial cable in accordance withan embodiment of the present disclosure;

FIG. 3A is an enlarged, cross-sectional view of the probe and hubassembly shown in FIG. 2A in accordance with an embodiment of thepresent disclosure;

FIG. 3B is an enlarged, cross-sectional view of the indicated area ofdetail of FIG. 3A, in accordance with an embodiment of the presentdisclosure;

FIG. 4 is an enlarged, cross-sectional view of the portion of thefeedline of a probe assembly of the present disclosure during theassembly process in accordance with an embodiment of the presentdisclosure;

FIG. 5 is an enlarged, cross-sectional view of the portion of thefeedline of a probe assembly of the present disclosure during theassembly process in accordance with an embodiment of the presentdisclosure;

FIG. 6 is an enlarged, cross-sectional view of the portion of acompleted feedline in accordance with an embodiment of the presentdisclosure;

FIG. 7A is a cross-sectional view of a portion of a probe assembly inaccordance with an embodiment of the present disclosure;

FIG. 7B is a longitudinal cross-sectional view of the probe assembly ofFIG. 7A depicting an array of temperature sensors.

FIG. 7C is a cross-sectional view of the probe assembly of FIG. 7Adepicting temperature sensors.

FIG. 8 is an enlarged, cross-sectional view of the distal portions ofthe probe feedline and radiating portions of a medical device, inaccordance with an embodiment of the present disclosure;

FIG. 9 is a screen shot of a CT based luminal navigation system inaccordance with an embodiment of the present disclosure;

FIG. 10 is a screen shot of a CT based luminal navigation system inaccordance with an embodiment of the present disclosure;

FIG. 11 is perspective view of a luminal navigation system in accordancewith an embodiment of the present disclosure;

FIG. 12 is a side view of a luminal catheter delivery assembly inaccordance with an embodiment of the present disclosure;

FIG. 13 is a perspective view of a catheter manipulation system inaccordance with an embodiment of the present disclosure;

FIG. 14 is a side view of a catheter in accordance with an embodiment ofthe present disclosure;

FIG. 15 is a screen shot of a CT based luminal navigation system inaccordance with an embodiment of the present disclosure;

FIG. 16A is a side view of a patient undergoing a VATS procedure inaccordance with an embodiment of the present disclosure;

FIG. 16B is an image as presented on a video monitor during a VATSprocedure in accordance with an embodiment of the present disclosure;

FIG. 17 is a perspective view of a marker in accordance with anembodiment of the present disclosure;

FIG. 18 is a perspective view of lung tissue having the marker of FIG.17 implanted therein;

FIG. 19 is a perspective view of the marker of FIG. 18 at a some timeafter implantation;

FIG. 20 is a perspective view of a marker in accordance with anembodiment of the present disclosure.

DETAILED DESCRIPTION

The present disclosure is generally directed to a microwave ablationprobe and a system for placement of the probe in a desired locationwithin the body. One aspect of the present disclosure is implementingthe percutaneous microwave ablation probe in combination with thei-Logic® target identification, navigation, and marker placement systemsdeveloped by superDimension, Ltd. In particular the present disclosuredescribes devices and systems for the treatment of lung cancer and otherlung diseases through microwave ablation of targets identified in thepatient for treatment, however the application of the present disclosureand the embodiments described herein are not limited to application ofany particular tissue or organ for treatment, indeed, it is contemplatedthat the systems and methods of the present disclosure may be used totreat liver tissue, kidney tissue, pancreatic tissue, gastrointestinaltissue, interstitial masses, and other portions of the body known tothose of skill in the art to be treatable via microwave ablation. Theseand other aspects of the present disclosure are described in greaterdetail below.

Hereinafter, embodiments of energy-delivery devices with a fluid-cooledprobe assembly and systems including the same of the present disclosureare described with reference to the accompanying drawings. Likereference numerals may refer to similar or identical elements throughoutthe description of the figures. As shown in the drawings and as used inthis description, and as is traditional when referring to relativepositioning on an object, the term “proximal” refers to that portion ofthe apparatus, or component thereof, closer to the user and the term“distal” refers to that portion of the apparatus, or component thereof,farther from the user.

This description may use the phrases “in an embodiment,” “inembodiments,” “in some embodiments,” or “in other embodiments,” whichmay each refer to one or more of the same or different embodiments inaccordance with the present disclosure.

Electromagnetic energy is generally classified by increasing energy ordecreasing wavelength into radio waves, microwaves, infrared, visiblelight, ultraviolet, X-rays and gamma-rays. As it is used in thisdescription, “microwave” generally refers to electromagnetic waves inthe frequency range of 300 megahertz (MHz) (3×10⁸ cycles/second) to 300gigahertz (GHz) (3×10¹¹ cycles/second). As it is used in thisdescription, “ablation procedure” generally refers to any ablationprocedure, such as, for example, microwave ablation, radiofrequency (RF)ablation, or microwave or RF ablation-assisted resection.

As it is used in this description, “energy applicator” generally refersto any device that can be used to transfer energy from a powergenerating source, such as a microwave or RF electrosurgical generator,to tissue. For the purposes herein, the term “energy applicator” isinterchangeable with the term “energy-delivery device”. As it is used inthis description, “transmission line” generally refers to anytransmission medium that can be used for the propagation of signals fromone point to another. As it is used in this description, “fluid”generally refers to a liquid, a gas or both.

As it is used in this description, “length” may refer to electricallength or physical length. In general, electrical length is anexpression of the length of a transmission medium in terms of thewavelength of a signal propagating within the medium. Electrical lengthis normally expressed in terms of wavelength, radians or degrees. Forexample, electrical length may be expressed as a multiple orsub-multiple of the wavelength of an electromagnetic wave or electricalsignal propagating within a transmission medium. The wavelength may beexpressed in radians or in artificial units of angular measure, such asdegrees. The electrical length is in general different from the physicallength. By the addition of an appropriate reactive element (capacitiveor inductive), the electrical length may be made significantly shorteror longer than the physical length.

Various embodiments of the present disclosure provide an energy-deliverydevice with a fluid-cooled probe assembly including a balun andtemperature sensor disposed in association with the balun. Embodimentsmay be suitable for utilization in open surgical applications.Embodiments may be suitable for utilization with hand-assisted,endoscopic and laparoscopic surgical procedures such as Video AssistedThoracic Surgery. Embodiments may be implemented using electromagneticradiation at microwave frequencies, RF frequencies or at otherfrequencies. An electrosurgical system including the presently disclosedenergy-delivery device with a fluid-cooled probe assembly disposed influid communication with a coolant supply system via a hub 40 accordingto various embodiments is configured to operate at frequencies betweenabout 300 MHz and about 10 GHz. During operation, cooling the probeassembly may enhance the overall heating pattern of the antennaassembly, prevent damage to the antenna assembly, and/or prevent harm tothe clinician or patient.

Various embodiments of the presently disclosed energy-delivery devicewith a fluid-cooled probe assembly including a balun and temperaturesensor disposed in association with the balun are suitable for microwaveor RF ablation and for use to pre-coagulate tissue for microwave or RFablation-assisted surgical resection. Although various methods describedhereinbelow are targeted toward microwave ablation and the completedestruction of target tissue, it is to be understood that methods fordirecting electromagnetic radiation may be used with other therapies inwhich the target tissue is partially destroyed or damaged, such as, forexample, to prevent the conduction of electrical impulses within hearttissue. In addition, although the following description describes theuse of a dipole microwave antenna, the teachings of the presentdisclosure may also apply to a monopole, helical, or other suitable typeof microwave antenna or RF electrode.

FIG. 1 is an exploded view of a medical device 10 in particular themedical device 10 is a microwave antenna. Medical device 10 includes anouter tubular member 30, an inner tubular member 35, a feedline 14, anantenna assembly 12, and a tip 19, which, when assembled, form a probeassembly, or portions thereof. Medical device 10 generally includes twohousing halves 21 and 22, which, when assembled, form a handle body 23.Handle body 23 defines a handle-body chamber 26 therein. Medical device10 includes a hub 40 (as well as other components described herein)disposed, at least in part, within the handle-body chamber 26.

Hub 40 includes a hub body 43 defining a hub-body chamber 46 therein.Medical device 10 includes a hub cap 150 and a hub divider 160, whichare configured to be receivable within the hub-body chamber 46 insealing engagement with the inner walls of the hub body 43. Outertubular member 30, the inner tubular member 35, the hub 40, and thecomponents cooperative therewith (e.g., hub cap 150 and hub divider 160)are adapted to maintain fluid flow to the antenna assembly 12. Hub body43 generally includes a first port 41 and a second port 42, e.g., toallow fluid communication with a coolant supply system (e.g., coolantsupply system 50 shown in FIG. 2A) via one or more coolant paths (e.g.,first coolant path 16 and second coolant path 18 shown in FIG. 2A).First port 41 and the second port 42 may be of any suitable shape, e.g.,rectangular, cylindrical, etc., and may include a groove adapted toreceive an o-ring or other suitable sealing element.

In some embodiments, the hub body 43 may include one or more mechanicalinterfaces, e.g., recess 45, adapted to matingly engage with one or morecorresponding mechanical interfaces (e.g., tab 70 shown in FIG. 2A)associated with the handle body 23, e.g., to align the hub 40 within thehandle body 23 and/or to fixedly secure the hub 40 within thehandle-body chamber 26. Similarly, each of the housing halves 21, 22 mayinclude a series of mechanical interfacing components, e.g., alignmentpins 74, 76, and 78, configured to matingly engage with a correspondingseries of mechanical interfaces (not shown), e.g., to align the twohousing halves 21, 22 about the components and assemblies of the medicaldevice 10. It is contemplated that the housing halves (as well as othercomponents described herein) may be assembled together with the aid ofalignment pins, snap-like interfaces, tongue and groove interfaces,locking tabs, adhesive ports, etc., utilized either alone or incombination for assembly purposes.

Hub divider 160 is configured and utilized to divide the hub-bodychamber 46 into a first chamber, e.g., disposed in fluid communicationwith the first port 41, and a second chamber, e.g., disposed in fluidcommunication with the second port 42. The first chamber (e.g., firstchamber 147 shown in FIG. 3A) generally fluidly connects the first port41 to the inner tubular member 35. The second chamber (e.g., secondchamber 143 shown in FIG. 3A) generally fluidly connects the second port42 to the inner tubular member 30.

In some embodiments, the inner walls of the hub body 43 may include aconfiguration of engagement portions adapted to provide sealingengagement with the hub cap 150 and/or the hub divider 160. In someembodiments, as shown in FIG. 1, an o-ring 157 is provided forengagement with the hub cap 150. O-ring 157 may provide sealing forcethat permits flexing and/or other slight movement of the hub cap 150relative to the hub 40 under fluid-pressure conditions. Hub cap 150 andthe hub divider 160 are described in more detail later in thisdisclosure with reference to FIG. 3A.

Outer tubular member 30 and the inner tubular member 35 may be formed ofany suitable non-electrically-conductive material, such as, for example,polymeric or ceramic materials. In some embodiments, as shown in FIGS.3A and 3B, the inner tubular member 35 is coaxially disposed around thefeedline 14 and defines a first lumen 37 therebetween, and the outertubular member 30 is coaxially disposed around the inner tubular member35 and defines a second lumen 33 therebetween.

Probe assembly 20 generally includes an antenna assembly 12 having afirst radiating portion (e.g., distal radiating section 318 shown inFIG. 7A) and a second radiating portion (e.g., proximal radiatingsection 316 shown in FIG. 7A). Antenna assembly 12, which is describedin more detail later in this disclosure, is operably coupled by thefeedline 14 to a transition assembly 80 shown in FIG. 1, which isadapted to transmit the microwave energy, from the cable assembly 15 tothe feedline 14. A connector assembly 17 shown in FIG. 1 is adapted tofurther operably connect the medical device 10 to a microwave generator28 (shown in FIG. 2A).

Feedline 14 may be any suitable transmission line, e.g., a coaxialcable. In some embodiments, as shown in FIGS. 3A and 3B, the feedlineincludes an inner conductor 220, an outer conductor 224 coaxiallydisposed around the inner conductor 220, and a dielectric material 222disposed therebetween. Dielectric material 222 may be formed from anysuitable dielectric material, e.g., polyethylene, polyethyleneterephthalate, polyimide, or polytetrafluoroethylene (PTFE). Innerconductor 220 and the outer conductor 224 may be formed from anysuitable electrically-conductive material. In some embodiments, theinner conductor 220 is formed from a first electrically-conductivematerial (e.g., stainless steel) and the outer conductor 224 is formedfrom a second electrically-conductive material (e.g., copper).Electrically-conductive materials used to form the feedline 14 may beplated with other materials, e.g., other conductive materials, such asgold or silver, to improve their properties, e.g., to improveconductivity, decrease energy loss, etc. Feedline 14 may have anysuitable length defined between its proximal and distal ends. Inaccordance with various embodiments of the present disclosure, thefeedline 14 is coupled at its proximal end to a transition assembly 80and coupled at its distal end to the antenna assembly 12. Feedline 14 isdisposed at least in part within the inner tubular member 35.

FIG. 2A shows a medical device 10 incorporated into an operationalsystem including a microwave generator 28 and a coolant supply system50. Medical device 10 includes a probe assembly 20 and a handle assembly60. Probe assembly 20 generally includes the outer tubular member 30,the inner tubular member 35, the feedline 14, the antenna assembly 12,and the tip 19 shown in FIG. 1. Handle assembly 60 generally includes ahandle body 23 defining a handle-body chamber 26 therein. Medical device10 also includes the hub 40 shown in FIG. 1 (as well as other componentsdescribed herein) disposed, at least in part, within the handle-bodychamber 26.

Probe assembly 20 may include a balun 90 (shown in FIGS. 1 and 7)disposed proximal to and spaced apart a suitable length from the feedpint 322. The balun 90, which is described in more detail later in thisdisclosure, generally includes a balun short, a balun insulator, and anelectrically-conductive layer disposed around the outer peripheralsurface of the balun insulator, or portions thereof. In someembodiments, the probe assembly 20 includes a temperature sensor 102(e.g., shown in FIG. 7) disposed in association with the balun 90.

As shown in FIG. 2A, the probe 20 is operably coupled by a cableassembly 15 to a connector assembly 17. Connector assembly 17 is a cableconnector suitable to operably connect the medical device 10 to amicrowave generator 28. The connector may house a memory (e.g., anEEPROM) storing a variety of information regarding the cable assembly 15and the medical device 10. For example, the memory may includeidentification information that can be used by the microwave generator28 to ensure that only properly identified medical devices 10 areconnected thereto. In addition, the memory may store operatingparameters of the medical device 10 (e.g., time, power, and dosagelimits), cable compensation parameters of the cable assembly 15, andinformation regarding the usage of the medical device 10 or the cableassembly 15. Usage monitoring may enable limiting re-use of the medicaldevice 10 beyond a certain number of energizations or a single use ofthe device. Such usage limitations may optionally be reset viareprocessing as is commonly understood in the art. Still further, theconnector assembly 17 may include sensor electronics related toradiometry and temperature sensing as described elsewhere herein. Cableassembly 15 may be any suitable, flexible transmission line, andparticularly a coaxial cable as shown in FIG. 2B, including an innerconductor 2220, a dielectric material 2222 coaxially surrounding theinner conductor 2220, and an outer conductor 2224 coaxially surroundingthe dielectric material 2222. Cable assembly 15 may be provided with anouter coating or sleeve 2226 disposed about the outer conductor 2224.Sleeve 2226 may be formed of any suitable insulative material, and maybe may be applied by any suitable method, e.g., heat shrinking,over-molding, coating, spraying, dipping, powder coating, and/or filmdeposition.

During microwave ablation the probe 20 is inserted into or placedadjacent to tissue and microwave energy is supplied thereto. One or morevisualization techniques including Ultrasound, computed tomography (CT),fluoroscopy, and direct visualization may be used to accurately guidethe probe 100 into the area of tissue to be treated, as will bedescribed in detail below. Probe 20 may be placed percutaneously orsurgically, e.g., using conventional surgical techniques by surgicalstaff. A clinician may pre-determine the length of time that microwaveenergy is to be applied. Application duration may depend on many factorssuch as tumor size and location and whether the tumor was a secondary orprimary cancer. The duration of microwave energy application using theprobe 20 may depend on the progress of the heat distribution within thetissue area that is to be destroyed and/or the surrounding tissue.

According to various embodiments, the probe assembly 20 is configured tocirculate coolant fluid “F”, e.g., saline, water or other suitablecoolant fluid, to remove heat generated by the antenna assembly 12and/or heat that may be generated along the length of the feedline 14,or portions thereof, during the delivery of energy.

In some embodiments, as shown in FIG. 3B, the first lumen 37 is utilizedas a fluid inflow conduit and the second lumen 33 is utilized as a fluidoutflow conduit. In other embodiments, the first lumen 37 may serve as afluid outflow conduit and the second lumen 33 may serve as a fluidinflow conduit. Outer tubular member 30 and/or the inner tubular member35 may be adapted to circulate coolant fluid therethrough, and mayinclude baffles, multiple lumens, flow restricting devices, or otherstructures that may redirect, concentrate, or disperse flow depending ontheir shape. The size and shape of the inner tubular member 35, theouter tubular member 30, the first lumen 37, and the second lumen 33 maybe varied from the configuration depicted in FIGS. 3A and 3B.

In some embodiments, at least a portion of the inner tubular member 35and/or at least a portion of the outer tubular member 30 (e.g., a distalportion) may include an integrated, spiraling metallic wire to addshape-memory properties to the probe 20 to aid in placement. In someembodiments, the inner tubular member 35 and/or the outer tubular member30 may increase in stiffness and exhibit increased shape-memoryproperties along their length distally toward the antenna assembly 12.

In some embodiments, the first port 41 and the second port 42 arecoupled in fluid communication with a coolant supply system 50 via oneor more coolant paths 16 and 18 coupled to and in fluid communicationwith the probe 20 via first and second chambers, 147 and 143 as shown inFIG. 3A. Coolant supply system 50 may be adapted to circulate coolantfluid “F” into and out of the medical device 20. Coolant source 52 maybe any suitable housing containing a reservoir of coolant fluid “F”, andmay maintain coolant fluid “F” at a predetermined temperature. Forexample, the coolant source 52 may include a cooling unit (not shown)capable of cooling the returning coolant fluid “F” from the antennaassembly 12 via the hub 40.

Coolant fluid “F” may be any suitable fluid that can be used for coolingor buffering the probe assembly 20, e.g., deionized water, or othersuitable cooling medium. Coolant fluid “F” may have dielectricproperties and may provide dielectric impedance buffering for theantenna assembly 12. Coolant fluid “F” composition may vary dependingupon desired cooling rates and the desired tissue impedance matchingproperties. Various fluids may be used, e.g., liquids including, but notlimited to, water, saline, perfluorocarbon, such as the commerciallyavailable Fluorinert® perfluorocarbon liquid offered by Minnesota Miningand Manufacturing Company (3M), liquid chlorodifluoromethane, etc. Inother variations, gases (such as nitrous oxide, nitrogen, carbondioxide, etc.) may also be utilized as the cooling fluid. In yet anothervariation, a combination of liquids and/or gases, including, forexample, those mentioned above, may be utilized as the coolant fluid“F”.

Coolant supply system 50 generally includes a first coolant path 16leading from the coolant source 52 to the first port 41 (also referredto herein as the fluid inlet port), and a second coolant path 18 leadingfrom the second port 42 (also referred to herein as the fluid outletport) to the coolant source 52. In some embodiments, the first coolantpath 16 includes a coolant supply line 31, e.g., leading from thecoolant source 118 to the fluid inlet port 41, and the second coolantpath 18 includes a coolant supply line 32, e.g., leading from thecoolant source 52 to fluid outlet port 42. In some embodiments, thefirst coolant path 16 includes a fluid-movement device (not shown)configured to move coolant fluid “F” through the first coolant path 16.Second coolant path 18 may additionally, or alternatively, include afluid-movement device (not shown) configured to move coolant fluid “F”through the second coolant path 18. Examples of coolant supply systemembodiments are disclosed in commonly assigned U.S. patent applicationSer. No. 12/566,299 filed on Sep. 24, 2009, entitled “OPTICAL DETECTIONOF INTERRUPTED FLUID FLOW TO ABLATION PROBE”, and U.S. application Ser.No. 13/835,625 filed on Mar. 15, 2013 entitled “RECIRCULATING COOLINGSYSTEM FOR ENERGY DELIVERY DEVICE” the disclosure of which isincorporated herein by reference.

FIG. 3A shows the probe assembly 20 disposed in part within the hub 40,wherein the hub cap 150 and the hub divider 160 are disposed in sealingengagement with the inner walls of the hub body 43, and a proximalportion of the probe assembly 20 is disposed in association with the hubcap 150 and hub divider 160. Hub divider 160 generally divides thehub-body chamber 46 (shown in FIG. 1) into a first chamber 147 a secondchamber 143, respectively. First chamber 147 is disposed in fluidcommunication with the first port 41. Second chamber 143 is disposed influid communication with the second port 42. In some embodiments, asshown in FIG. 3A, the proximal end of the inner tubular member 35 isdisposed within the first chamber 147, wherein the first lumen 37 isdisposed in fluid communication with the first port 41, and the proximalend of the outer tubular member 30 is disposed within the second chamber143, wherein the second lumen 33 is disposed in fluid communication withthe second port 42.

In some embodiments, as shown in FIG. 3A, the inner tubular member 35includes a first portion having a first outer diameter, a second portionhaving a second outer diameter greater than the first outer diameter,and a neck portion 36 disposed therebetween. In some embodiments, theopening in the hub divider 160 is configured for sealing engagement withthe second portion of inner tubular member 35 having the second outerdiameter. In some embodiments, located within the interior of the secondportion of the inner tubular member 35 is a high hoop strength metalcylinder 38. The metal cylinder 38 engages the inner diameter of theinner tubular member 35. The hub divider 160 is formed of an elastomericmaterial and when forced into place within the hub 40, as shown in FIG.3A, the elastomeric material of the hub divider 160 creates an improvedwater tight seal separating the first hub chamber 147 from the secondhub chamber 143. The metal cylinder 38 improves this seal by ensuringbetter contact between the elastomeric material of the hub divider 160and the inner tubular member 35 upon application of lateral forces tothe hub divider 160.

Hub body 43 may be configured to sealingly engage the coolant supplylines forming coolant paths 16 and 18 to fluid inlet port 41 and fluidoutlet port 42. Fluid inlet port 41 and the fluid outlet port 42 mayhave any suitable configuration, including without limitationnipple-type inlet fittings, compression fittings, and recesses, and mayinclude an o-ring type elastomeric seal.

FIG. 3B shows a portion of the probe assembly 20 of FIG. 3A includingthe first lumen 37, shown disposed between the outer tubular member 30and inner tubular member 35, the second lumen 33, shown disposed betweenthe inner tubular member 35 and the feedline 14, and a transmission line11 extending longitudinally within the second lumen 33. As indicated bythe direction of the arrow-headed lines in FIG. 3B, the first lumen 37serves as an inflow conduit for coolant fluid “F” and the second lumen33 serves as an outflow conduit for coolant fluid “F,” however as notedabove these could be reversed without departing from the scope of thepresent disclosure.

As shown in FIG. 1, Probe assembly 20 may include a balun 90 disposedproximal to and spaced apart a suitable length from the feed point 322.In some embodiments, the balun 90 may be a quarter-wavelength, ¼λ,balun, or a ¾λ balun. Odd harmonics (e.g., ¼λ, ¾λ, etc.) may cause acurrent null at the balun entrance, which helps maintain a desiredradiation pattern.

During a manufacturing sequence in accordance with the presentdisclosure, the component parts of the balun 90, according to theembodiment shown in FIG. 6, are assembled, and, during the manufacturingsequence, as illustratively depicted in FIGS. 4-6, a temperature sensor102 is coupled to the balun short 302 of the balun 90.

FIG. 4 shows a portion of the feedline 14 including the inner conductor220, the outer conductor 224 coaxially disposed around the innerconductor 220, and the dielectric material 222 disposed therebetween,shown with a balun short 302 coaxially disposed around a portion of theouter conductor 224. During medical device assembly, balun short 302 iscoupled, deposited or otherwise formed onto, or joined to, the outerconductor 224. Balun short 302 may be formed as a single structure andelectrically coupled to the outer conductor 224, e.g., by solder orother suitable electrical connection. Balun short 302 may be formed ofany suitable electrically-conductive materials, e.g., copper, gold,silver or other conductive metals or metal alloys. In some embodiments,the balun short 302 has a generally ring-like or truncated tubularshape. Balun short 302 is electrically coupled to the outer conductor224 of the feedline 14 by any suitable manner of electrical connection,e.g., soldering, welding, or laser welding. The size and shape of thebalun short 302 may be varied from the configuration depicted in FIG. 4.

FIG. 4 further depicts a dielectric layer 304 (also referred to hereinas a balun insulator) coaxially disposed around the outer conductor 224and coupled thereto. Balun insulator 304 may be formed of any suitableinsulative material, including, but not limited to, ceramics, water,mica, polyethylene, polyethylene terephthalate, polyimide,polytetrafluoroethylene (PTFE) (e.g., Teflon®, manufactured by E. I. duPont de Nemours and Company of Wilmington, Del., United States), glass,metal oxides or other suitable insulator, and may be formed in anysuitable manner. In some embodiments, as shown in FIG. 4, the baluninsulator 304 is a dielectric sleeve. Balun insulator 304 may be grown,deposited or formed by any other suitable technique. In someembodiments, the balun insulator 304 is formed from a material with adielectric constant in the range of about 1.7 to about 10.

FIG. 4 further depicts a temperature sensor 102 disposed in contact witha proximal end of the balun short 302. Temperature sensor 102 is coupledto a transmission line 11 extending generally along a longitudinal axisof the feedline 14. In some embodiments, the temperature sensor 102 is athermocouple and the transmission line 11 is a thermocouple wire. Thethermocouple wire may be a two lead wire thermocouple wire, for exampleit may be comprised of an insulated (anodized) side-by-side constantinewire and a copper wire. The balun short 302 may include an engagementelement 306 adapted to engage with the temperature sensor 102, e.g., tofacilitate electrical and mechanical coupling of the temperature sensor102 and the balun short 302. In some embodiments, the engagement element306 may be a groove, slot, or recess cut into the balun short 302.Alternatively, the temperature sensor 102 may be soldered to balun short302. Placement of the thermocouple 102 directly against the balun short302 improves the sensitivity and thermo-profiling characteristics of themedical device 10, particularly as compared to traditional thermocouplesin microwave ablation devices, which measure the temperature of thecooling fluid. As will be appreciated by those of skill in the art thetemperature of the coolant will lag the temperature of the balun itself,and thus provide only approximate indications of the temperature of theelements which are heated during operation. As a result, in instanceswhere little or no coolant is flowing, the temperature of the balun 90and feedline 14 associated therewith can increase faster than that ofthe coolant and result in damage to medical device 10 even beforetriggering a shut-off of the system based on the temperature thecoolant. Accordingly, improved safety and performance can be achieved bydirect sensing of temperature of the balun 90.

Still further, FIG. 4 depicts a heat-shrink tubing 308 disposed in afirst configuration around the outer conductor. During assembly, theheat-shrink tubing 308 is utilized to secure a portion of thetransmission line 11 to the feedline 14. Heat-shrink tubing 308 may beany suitable tubing material with the capability to respond to heat andbind around an object, and may have any suitable length. In someembodiments, the heat-shrink tubing 308 may be a thermoplastic.

FIG. 5 shows the feedline of FIG. 4 following application of heat to theheat shrink tubing 308. During assembly, securing a portion of thetransmission line 11 to the feedline 14, as shown in FIG. 6 keeps thetransmission line stable and helps to maintain the electrical andmechanical coupling of the temperature sensor 102 and the balun short302 during subsequent assembly operations. FIG. 5 further shows a secondheat shrink tubing 310 disposed in a first configuration.

The tubing member 310 includes an inner layer of anelectrically-conductive material 312. Electrically-conductive layer 312may be formed of any suitable electrically-conductive material, e.g.,metallic material. In one embodiment the metallic material ofelectrically conductive layer 312 is formed of a silver ink deposited orlayered on an interior surface of the heat shrink tubing 310. The heatshrink tubing member 310 may have a length from about 1 to about 3inches in length. However, the shape and size of the tubing member 310and balun insulator 304 may be varied from the configuration depicted inFIG. 5 without departing from the scope of the present disclosure.Indeed, though described as one embodiment, the orientation andimplementation of the feed line 14 as well as other aspects of thepresent disclosure is not so limited. For example, the feed line 14 mayincorporate one or more aspects of the ablation system described in U.S.application Ser. No. 13/836,203 filed on Mar. 15, 2013 entitled“MICROWAVE ABLATION CATHETER AND METHOD OF UTILIZING THE SAME,” theentire content of which is incorporated herein by reference.

FIG. 6 shows the balun 90 after the application of thermal energy to theheat shrink tubing 310 and the resultant shrinkage. As shown FIG. 16,the electrically-conductive material 312 is disposed in intimate contactwith the balun short 302 and a portion of the balun insulator 304. Insome embodiments, as shown in FIG. 6, a portion of the balun insulator304 may extend distally beyond the distal end of the heat shrink tubing310 and electrically conductive layer 312, to create gap 314. Gap 314improves the microwave performance of the probe 20 and can assist inachieving a desired ablation pattern. More specifically, the gap 314ensures adequate coupling of microwave energy from the proximalradiating section 316 into the balun 90, improving the performance ofthe balun 90 over a wide range of tissue dielectric conditions. Further,FIG. 6 shows the heat shrink tubing 310 securing the portion of thetransmission line 11 between heat shrink tubing 308 and the balun short302 to the feedline 14 preventing its movement and substantiallypreventing the temperature sensor 102 from being removed from physicalcontact with the balun short 302.

FIG. 7A shows a portion of the probe assembly 100 that includes thebalun 90 of FIG. 6 connected to the antenna assembly 12. In operation,microwave energy having a wavelength, lambda (λ), is transmitted throughthe antenna assembly 12 and radiated into the surrounding medium, e.g.,tissue. The length of the antenna for efficient radiation may bedependent on the effective wavelength, λ_(eff), which is dependent uponthe dielectric properties of the treated medium. Antenna assembly 12through which microwave energy is transmitted at a wavelength, λ, mayhave differing effective wavelengths, λ_(eff), depending upon thesurrounding medium, e.g., liver tissue as opposed to breast tissue, lungtissue, kidney tissue, etc.

Antenna assembly 12, according to the embodiment shown in FIG. 7,includes a proximal radiating section 316 having a length “L1”, a distalradiating section 318 including an electrically-conductive element 320having a length “L2”, and a feed point 322 disposed therebetween. Insome embodiments, the proximal radiating section 316 may have a length“L1” in a range from about 0.05 inches to about 0.50 inches.Electrically-conductive element 320 may be formed of any suitableelectrically-conductive material, e.g., metal such as stainless steel,aluminum, titanium, copper, or the like. In some embodiments, theelectrically-conductive element 320 may have a length “L2” in a rangefrom about 0.15 inches to about 1.0 inches.

As shown in FIG. 7A electrically-conductive element 320 has a steppedconfiguration, such that the outer diameter of the distal portion 324 isless than the outer diameter of the proximal portion 326. Further, theinner conductor 220 of the feedline 14 is arranged such that it extendspast the distal end of the insulator 222 and into the proximal portion326 of the electrically-conductive element 320. A hole 328, formed inthe proximal portion 326 approximately at 90 degrees to the innerconductor 220 allows for solder, a set screw, or other securingmechanisms to physically secure the electrically conductive element 320to the inner conductor 220 and therewith the feedline 14 of the medicaldevice 20.

FIG. 7B depicts a further embodiment of the present disclosure in whichrather than or in addition to the temperature sensor 102 located at thebalun short 302, one or more temperature sensors 502 are placed in or onthe outer tubular member 30. The outer tubular member 30 formed forexample of an epoxy filled glass fiber material. As such the outertubular member may be formed of a plurality of layers of glass fibermaterial. During the manufacturing process, one or more temperaturesensors 502 may be imbedded in the layup of the glass fiber material.The temperature sensors 502, include wires 504 which connect back to thehandle body 23 and ultimately generator 28 or a separate temperaturecontroller (not shown). As an alternative to placing the temperaturesensors within the layup of the outer tubular member 30, the outertubular member 30 may be first formed and then subsequently machined toinclude one or more slots in which the temperature sensors 502 and wires504 may be secured, using for example an epoxy material.

According to one embodiment at least one temperature sensor 502 islocated at approximately the proximal end of the balun 90. This isapproximately the same location as the temperature sensor 102 of FIG. 6(i.e. about three inches from the distal tip of the medical device 10),but on the outer tubular member 30 as opposed to the balun short 302.This location has been identified as particularly useful in sensing twoproblems that can occur during operation, no fluid in the medical device10, and no fluid flow through the medical device 10. These can occurwhere the clinician fails to connect the cooling system to the medicaldevice or where the clinician fails to turn on the cooling fluid pump,or where there is some other cooling system malfunction. In anyinstance, the result of the lack of fluid or fluid flow along the outertubular member 30 can result in it heating to 45° C., which can lead tounintended cell death in the surrounding tissue. The temperature sensors502 can be employed as a safety indicator and cause the generator 28 toshut down and or issue an alarm as temperatures approach apre-determined threshold, and thus prevent injury to the patient.

While described above as a single temperature sensor 502, multipletemperature sensors may be used as shown in FIG. 7A. Alternatively, anarray of the temperature sensors 502 located at different positionsalong the length of the outer tubular member 30 may be employed todetermine the temperature at different positions along its length asshown in FIG. 7B. These may be at approximately 0.8, 1.0. 1.2, and 1.4inches from the distal tip of the medical device 10. Using this array, athermographic profile of the tissue can be created for review andanalysis during and after the procedure. For example by sensing thetemperature at each temperature sensor 502 the progression of thetreatment may be monitored or a terminal threshold of the treatment maybe monitored for and end the treatment. The temperature sensors 502 ofthe array can detect the rising temperature of the ablation field andcan be correlated with the ablation growth in the surrounding tissue.

The array of temperature sensors 502 as shown in FIG. 7B may be inaddition to the temperature sensor 502 on the outer tubular member atapproximately the balun short 302, and/or the temperature sensor 102 incontact with the balun short 302.

In a further embodiment, and as depicted in FIG. 7C, the temperaturesensors are located as near the outer periphery of the outer tubularmember 30 as possible. In such an embodiment the temperature sensor thusprovides a closer approximation of the temperature of the tissueimmediately surrounding the outer tubular member 30.

The temperature sensors 502 may be incorporated as part of a temperaturemonitoring system, e.g., microwave thermometry incorporated into themicrowave generator 28 to provide feedback to the generator, oralternatively the temperature monitoring system may be housed in aseparate box (not shown) providing audible or visual feedback to theclinician during use of the medical device 10. The temperature sensors502 are utilized to observe/monitor tissue temperatures in or adjacentan ablation zone. The temperature monitoring system can be, for example,a radiometry system, a thermocouple based system, or any other tissuetemperature monitoring system known in the art. In either embodiment,the temperature monitoring system may be configured to provide tissuetemperature and ablation zone temperature information to the microwavegenerator 28 (or other suitable control system).

In at least one embodiment, the tissue temperature and/or ablation zonetemperature information may be correlated to specific known ablationzone sizes or configurations that have been gathered through empiricaltesting and stored in one or more data look-up tables and stored inmemory of the temperature monitoring system and/or the microwavegenerator 28. The configurations may also be based on the observed sizeand type of tissue to be ablated. Still further, the temperaturemonitoring system may enable a clinician, having ascertained the size ofa target to enter the size into the system and have the system calculatea proposed course of treatment including one or more of a power setting,a number of medical device to be employed, and the duration or number ofserial energy applications to achieve a desired ablation zone effectivefor treating the target tissue. The data look-up tables may beaccessible by a processor of the temperature sensing system and/ormicrowave generator 28 and accessed by the processor while the medicaldevice 10 is energized and treating target tissue. In this embodiment,the temperature sensors 502 provide tissue temperature and/or ablationzone temperature to the microprocessor which then compares the tissuetemperature and/or ablation zone temperature to the ablation zone sizesstored in the data look-up tables. The microprocessor may then send acommand signal to one or more modules of the temperature sensingmonitoring system and/or the generator 28 to automatically adjust themicrowave energy output to the medical device 10. Alternatively, amanual adjustment protocol may be utilized to control the microwaveenergy output to the medical device 10. In this embodiment, themicroprocessor may be configured to provide one or more indications(e.g., visual, audio and/or tactile indications) to a user when aparticular tissue temperature and/or ablation zone temperature ismatched to a corresponding ablation zone diameter or configuration. Thetemperature monitoring system can incorporated into one or morecomponents (e.g., a software graphical interface configured for displayon a monitor 1006

FIG. 8 shows a distal portion of the probe assembly 20 including the tip19, distal portions of the inner and outer tubular members, 35 and 30,respectively, and an inflow/outflow junction 39. Inflow/outflow junction39 is defined, at least in part, by the outer tubular member 30 andextends distally from the distal end 34 of inner tubular member 35. Tip19 generally includes a tip body 402 defining an interior chamber 404disposed within a proximal portion of the tip 19. In some embodiments,the interior chamber 404 includes a distal chamber portion 406 and aproximal chamber portion 408 adapted to be coupled in fluidcommunication with the inflow/outflow junction 39. Tip body 402 includesa lateral portion 410, and may include a tapered portion 412, which mayterminate in a sharp tip 414 to allow for insertion into tissue withminimal resistance. Tapered portion 412 may include other shapes, suchas, for example, a tip 414 that is rounded, flat, square, hexagonal, orcylindroconical. In some embodiments, the outer diameter of the lateralportion 410 of the tip body 402 is substantially the same as the outerdiameter of the outer tubular member 30.

Tip 19 may be formed of a material having a high dielectric constant,and may be a trocar, e.g., a zirconia ceramic. In some embodiments, theinterior chamber 404 is configured to receive a distal end 324 of theelectrically-conductive element 320 of the antenna assembly 12. Theplacement of the distal end 324 within interior chamber 404 incombination the shape of the tip 19 dielectrically bufferselectromagnetic energy within close proximity to the antenna assembly12, specifically around the distal end 324 of the electricallyconductive element 320. This arrangement promotes a desirableelectromagnetic wave pattern whereby tissue beyond the tip 19 is heatedsufficiently to kill diseased cells residing distally away from theprobe placement. The projection of electromagnetic energy distally fromthe tip 19 from the antenna assembly 12 may be described as a microwavefield lensing effect. In some embodiments, as shown in FIG. 8, the innerwall of the tip body 402 defining the interior chamber 404 includes atapered portion 416, e.g., to facilitate the placement of the distal end324 of the electrically-conductive element 320 into the chamber 404,and/or to facilitate fluid flow between the interior chamber 404 and theinflow/outflow junction 39. The shape and size of the distal chamberportion 406 and the proximal chamber portion 408 may be varied from theconfiguration depicted in FIG. 8A without departing from the scope ofthe present disclosure.

In some embodiments, as shown in FIG. 8, the tip body 402 includes agenerally L-shaped engagement portion 418 defined, at least in part, bya lateral portion 420 of the tip body 402, wherein the engagementportion 418 is adapted to engage an end portion and the inner surface ofthe outer tubular member 30. In some embodiments, the outer diameter ofthe lateral portion 420 of the tip body 402 is less than the innerdiameter of the outer tubular member 30, e.g., to provide space for aheat-resistant adhesive material (e.g., material 422 shown in FIG. 8),or other suitable material.

FIG. 8 shows the tip 19 disposed in association with the outer tubularmember 30, wherein the distal end 324 of the electrically-conductiveelement 320 of the antenna assembly 12 is disposed within a portion ofthe interior chamber 404. Tip 19 and the outer tubular member 30 may besealingly connected together with a heat-resistant adhesive material 422or other suitable material, e.g., disposed between the inner wall of theouter tubular member 30 and lateral surface 420 of the tip 19. It is tobe understood, however, that sealing engagement between the tip 19 andthe outer tubular member 30 may be provided by any suitable technique.

The above-described energy-delivery devices with a fluid-cooled probeassembly are capable of directing energy into tissue, and may besuitable for use in a variety of procedures and operations. Theabove-described energy-delivery device embodiments may be suitable forutilization with hand-assisted, endoscopic and laparoscopic surgicalprocedures. The above-described energy-delivery device embodiments mayalso be suitable for utilization in open surgical applications.

One aspect of the present disclosure is the use of the microwaveablation devices described above used for treatment of cancers and otherdiseases of the lungs. Location and treatment of lung diseases,particularly cancers due to smoking, is quite challenging due to thetortuous paths of the lung passages, the extremely small size ofperipheral lung passages, the movement of the lungs during bothdiagnostics procedures and treatment.

As a practical matter the most effective method of identifying targetsinvolves the use of a computed tomographic (CT) image. By way ofintroduction, the use of CT as a diagnostic tool has now become routineand CT results are now frequently the primary source of informationavailable to the practitioner regarding the size and location of alesion. This information is used by the practitioner in planning anoperative procedure such as a biopsy, but is only available as “offline”information which must typically be memorized to the best of thepractitioner's ability prior to beginning a procedure. As will bediscussed below, in addition to inputting target information,integration with the CT data provides improved system functionality,thereby greatly facilitating the planning of a pathway to an identifiedtarget as well as providing the ability to navigate through the body tothe target location.

One aspect of the present disclosure relates to a system and method forconstructing, selecting and presenting pathway(s) to a target locationwithin an anatomical luminal network in a patient. These embodiments ofthe present disclosure are particularly, but not exclusively, suited forguiding and navigating a probe through the bronchial airways of thelungs. This embodiment of the present disclosure includes a preoperativeand an operative component. The preoperative component is conductedprior to navigation and can be categorized as pathway planning. Theoperative component is conducted during navigation and can becategorized as navigation.

The pathway planning phase includes three general steps, each of whichis described in more detail below. The first step involves using asoftware graphical interface for generating and viewing athree-dimensional model of the bronchial airway tree (“BT”). The secondstep involves using the software graphical interface for selection of apathway on the BT, either automatically, semi-automatically, ormanually, if desired. The third step involves an automatic segmentationof the pathway(s) into a set of waypoints along the path that can bevisualized on a display. It is to be understood that the airways arebeing used herein as an example of a branched luminal anatomicalnetwork. Hence, the term “BT” is being used in a general sense torepresent any such luminal network and not to be construed to only referto a bronchial tree, despite that the initials “BT” may not apply toother networks.

Using a software graphical interface 1001 as shown in FIG. 9, forgenerating and viewing a BT, starts with importing CT scan images of apatient's lungs, preferably in a DICOM format, into the software. Thedata may be imported into the software using any data transfer media,including but not limited to CDs, memory cards, network connections,etc. The software processes the CT scans and assembles them into athree-dimensional CT volume by arranging the scans in the order theywere taken and spacing them apart according to the setting on the CTwhen they were taken. The software may perform a data fill function tocreate a seamless three-dimensional model. The software uses thenewly-constructed CT volume to generate a three-dimensional map, or BT,of the airways. The three dimensional map can either be skeletonized,such that each airway is represented as a line, or it may be includeairways having dimensions representative of their respective diameters.Preferably, when the BT is being generated, the airways are marked withan airflow direction (inhalation, exhalation, or separate arrows foreach) for later use during the pathway generation step. The softwarethen displays a representation of the three-dimensional map 1003 on thesoftware graphical interface 1001.

FIG. 10 depicts a further software graphical interface 1013 in whichthree views of the CT image are presented along with a computergenerated model of the interior of the BT. As shown, the top left image1005 is the lateral view of the CT volume of the lungs, i.e. as thoughlooking parallel to the spine of the patient. The lower-left image 1007is a birds-eye view of the CT volume of the lungs. The upper-right image1009 is a side view of the CT volume of the lungs. Finally, thelower-right image 1011 is a three-dimensional perspective view inside avirtual airway of the BT. Cross-hairs 1015 span over three of the imagesto show the position in the CT image in all three planes.

A user presented with the graphical interface 1013 is able to scrollthrough the CT image, in any of the presented views and identify one ormore targets. These targets are typically masses or tumors that themedical professional would like to biopsy or treat, and to which themedical professional would like to use the system to navigate. Once oneor more targets are identified in the images 1005-1009, and selected bya medical professional using the target selection tool incorporated inthe software, the targets automatically appear on the image of the BT astargets 1017 in FIG. 10.

Next, the software selects a pathway to the target. In one embodiment,the software includes an algorithm that does this by beginning at theselected target and following lumina back to the entry point. Using theairways as an example, the target is first selected. The software thenselects a point in the airways nearest the target. If the point closestto the target is in an airway segment that is between branches, thesoftware has to choose between two directional choices. The pathway tothe target may be determined using airway diameter. Moving toward theentry point (the trachea) results in an increased airway diameter whilemoving distally results in a decreased airway diameter. If the pointclosest to the target is in an airway segment that includes one or morebranches, the choices are more numerous but the following the path ofthe greatest increase in airway diameter will still result in thecorrect path to the entry point. Though unlikely, in the event that anincorrect path is taken, the software would eventually detect aninevitable decrease in diameter, if this is the case, the software wouldautomatically abort that path and revert to the last decision-makingpoint. The algorithm will resume, blocking off the incorrect path as anoption.

After the pathway has been determined, or concurrently with the pathwaydetermination, the suggested pathway is displayed for user review.Preferably, the entire BT will be displayed with the suggested pathwayhighlighted in some fashion. The user will have zoom and pan functionsfor customizing the display. This is important as the software mayidentify a solution that rotation or zooming of the BT will show is lessthan ideal. For example, a planned route may include a 90 degree turn toreach the target. Such turns are nearly impossible for current cathetersystems, as will be described in greater detail below, to accomplish,particularly as the airway passages become smaller. Thus, by rotatingand zooming the image, a medical professional can determine a preferableroute (e.g., one where the target is accessed in a more direct line fromthe airway). There may be additional reasons for editing the pathway,for example, though the targeted lesion is closest to a particularairway, there may be an artery or a lobe division between the selectedairway and the target. Hence, it is important to provide the user withediting ability. In addition to the above described techniques fordetermining a pathway to a target, the present disclosure may alsoemploy the techniques described in commonly assigned U.S. applicationSer. No. 13/838,805 filed on Mar. 15, 2013 (H-IL-00087 (1988-87)entitled “PATHWAY PLANNING SYSTEM AND METHOD,” the entire contents ofwhich is incorporated herein by reference.

This image 1011 is a CT-based “virtual bronchoscopy” which depictssimulated views similar to the actual bronchoscope views. The technologyof virtual bronchoscopy is described in commonly assigned U.S. Pat. Nos.6,246,784 and 6,345,112 both to Summers et al., as well as thereferences cited therein, all of which are hereby incorporated herein byreference. Once the pathway is edited, as necessary, the user can followa fly-through virtual bronchoscopy image 1011. The software generates acolored line which represents the pathway determined above. The medicalprofessional is to follow the pathway through the trachea, and theairways until reaching the target. As can be appreciated, as the airwaysget smaller and smaller the ability of the software to resolve theairways becomes increasingly difficult, and the display 1011 mayeventually not depict a clear airway lumen. Regardless, the target 1017will be displayed in the computer generated image 1011 and allow theutilization of the system for pathway planning purposes.

Having identified a pathway in the BT connecting the trachea in a CTimage with a target, a system is necessary to reach the target forbiopsy of the target and eventually treatment if necessary. One suchsystem is depicted in FIG. 11. Specifically, FIG. 11 shows a patient1000 lying on an operating table 1002. A bronchoscope 1004 is insertedinto his lungs. Bronchoscope 1004 is connected to the monitoringequipment 1006, and typically includes a source of illumination and avideo imaging system. In certain cases, the devices of the presentdisclosure may be used without a bronchoscope, as will be describedbelow. A position measuring system monitors the position of the patient1000, thereby defining a set of reference coordinates. A particularlypreferred position measuring system is a six degrees-of-freedomelectromagnetic position measuring system according to the teachings ofU.S. Pat. No. 6,188,355 and published PCT Application Nos. WO 00/10456and WO 01/67035, which are incorporated herein by reference. In thiscase, a transmitter arrangement 1008 is implemented as a matt positionedbeneath patient 1000. A number of miniature sensors 1020 areinterconnected with a tracking module 1022 which derives the location ofeach sensor 1020 in 6 DOF (degrees of freedom). At least one, andpreferably three, reference sensors 1020 are attached to the chest ofpatient 1000 and their 6 DOF coordinates sent to a computer 1024 wherethey are used to calculate the patient coordinate frame of reference.

FIG. 12 depicts a catheter assembly 1030, constructed and operativeaccording to the teachings of the present disclosure. Catheter assembly1030 includes a locatable guide 1032 which has a steerable distal tip1034, a flexible body 1036 and, at its proximal end, a control handle1038. Guide 1032 is inserted into a sheath 1040 within which it islocked in position by a locking mechanism 1042. A position sensorelement 1044, operating as part of the position measuring system of FIG.11, is integrated with distal tip 1034 and allows monitoring of the tipposition and orientation (6 DOF) relative to the reference coordinatesystem.

There are several methods of steering the catheter 30. In a firstmethod, a single direction of deflection may be employed. Alternatively,a multi-directional steering mechanism with a manual direction selectormay be employed to allow selection of a steering direction by thepractitioner without necessitating rotation of the catheter body. FIG.13 depicts a system for multi-directional steering using at least three,and preferably four, elongated tensioning elements (“steering wires”)1048 are attached. Steering wires 1048 are deployed such that tension oneach wire individually will steer the tip towards a predefined lateraldirection. In the case of four wires, the directions are chosen to beopposite directions along two perpendicular axes. In other words, thefour wires are deployed such that each wire, when actuated alone, causesdeflection of said tip in a different one of four predefined directionsseparated substantially by multiples of 90°. For practical reasons ofease of manufacture and reliability, wires 1048 are preferablyimplemented as pairs of wires formed from a single long wire extendingfrom handle 1038 to tip 1034, bent over part of base 1046, and returningto handle 1038, as shown.

A third alternative employs a catheter assembly 1030 having a curved orhooked configuration as shown in FIG. 14. In such a system, it is thecatheter sheath 1040 that is formed with a curved tip 1050. Thelocatable guide 1032 is inserted into the sheath 1040 such that thesensor element 1044 projects from the distal tip of the sheath 1040. Thesheath 1040 and the locatable guide 1032 are locked together such thatthey are advanced together into the lung passages of the patient 1000.The user when needing to select a path for further insertion of thecatheter assembly 1030 simply rotates the locked together sheath 1040and locatable guide 1032. It has been found that the pre-forming of thecurved tip 1050 of the sheath 1040 facilitates advancement by requiringonly one hand of the user, and minimizing fatiguing motions such assqueezing of the control handle 1038 to release a locking mechanism orto advance the sheath 1040 or locatable guide 1032. This alternative iscurrently marketed by Covidien LP under the name EDGE®. Differingamounts of pre-curve implemented in the sheath 1040 can be used,however, common curvatures include 45, 90, and 180 degrees. The 180degree sheath has been found particular useful for directing thelocatable guide 1032 to posterior portions of the upper lobe of the lungwhich can be particularly difficult to navigate.

As noted above, the present disclosure employs CT data (images) for theroute planning phase. CT data is also used for the navigation phase. CTdata is preferable to other imaging modalities because it has its ownsystem of coordinates. Matching the two systems of coordinates, that ofthe CT and that of the patient, is commonly known as registration.Registration is generally performed by identifying locations in both theCT and on or inside the body, and measuring their coordinates in bothsystems.

Methods of manual and semi-automated registration of CT data and patientdata are described in detail in for example U.S. Pat. No. 7,233,820assigned to Covidien LP and incorporated herein by reference. Whilestill a viable methods of registration, because particularly manualregistration is somewhat time consuming and requires multiple steps,many practitioners rely on the automatic registration techniques thesoftware of the current disclosure enables. However, in some instances,particularly if the CT image data is not of sufficient quality it maystill be necessary or desirable to conduct manual registration.

Automatic registration has become the norm for most procedures becausewhile the manual fiducial point designation of the above referencedregistration techniques is highly effective, the choice of number ofpoints sampled necessarily represents a tradeoff between accuracy andefficiency. Similarly, while the semi-automated technique is a viableoption it requires an image sensor at the distal end of the catheterassembly which adds increased complexity to the system.

Automatic registration techniques are described in detail in commonlyassigned U.S. patent application Ser. No. 12/780,678, which isincorporated herein by reference. Automatic registration between adigital image of a branched structure and a real-time indicatorrepresenting a location of a sensor inside the branched structure isachieved by using the sensor 1044 to “paint” a digital picture of theinside of the structure. Once enough location data has been collected,registration is achieved. The registration is “automatic” in the sensethat navigation through the branched structure necessarily results inthe collection of additional location data and, as a result,registration is continually refined.

The automatic registration method comprises the following steps and asystem is adapted to perform the following steps: moving a locatableguide 1032 containing a location sensor 1044 within a branched structureof a patient 1000; recording data pertaining to locations of said sensorwhile said sensor is moving through said branched structure using thetransmitter arrangement 1008; comparing a shape resulting from said datato an interior geometry of passages of said three-dimensional model ofsaid branched structure; and determining a location correlation betweensaid shape and said three-dimensional model based on said comparison.

Another aspect of the method comprises the following steps performed bythe software of the present disclosure: identifying non-tissue space(e.g. air filled cavities) in said three-dimensional model; moving alocatable guide 1032 through at least one lumen of said branchedstructure while recording position data of a location sensor 1044 insaid locatable guide 1032; and aligning an image representing a locationof said probe with an image of said three-dimensional model based onsaid recorded position data and an assumption that said probe remainslocated in non-tissue space in said branched structure. Thus thesoftware is capable of performing steps of comparing a shape, anddetermining a location correlation, or aligning an image.

The registration techniques operates on the premises that (1) theendoscope remains in the airways at all times and (2) recording themovement of a sensor on an endoscope results in a vastly greater sampleset than recording discrete positions of a sensor on a stationaryendoscope.

The registration methods may be referred to as “feature-basedregistration.” When the CT scans are taken, the CT machine records eachimage as a plurality of pixels. When the various scans are assembledtogether to form a CT volume, voxels (volumetric pixels) appear and canbe defined as volume elements, representing values on a regular grid inthree dimensional space. Each of the voxels is assigned a number basedon the tissue density Hounsfield number. This density value can beassociated with gray level or color using well known window-levelingtechniques.

The sensing volume of the electromagnetic field of the transmitterarrangement 1008 is also voxelized by digitizing it into voxels of aspecific size compatible with the CT volume. Each voxel visited by thelocation sensor 1044 can be assigned a value that correlates to thefrequency with which that voxel is visited by the location sensor 1044.The densities of the voxels in the CT volume are adjusted according tothese values, thereby creating clouds of voxels in the CT volume havingvarying densities. These voxel clouds or clusters thus match theinterior anatomical features of the lungs.

By using a voxel-based approach, registration is actually accomplishedby comparing anatomical cavity features to cavity voxels, as opposed toanatomical shapes or locations to structure shapes or locations. Anadvantage of this approach is that air-filled cavities are of apredictable range of densities. Air filled cavities may be identified asnon-tissue space in the CT volume, which is a three-dimensional model.The location sensor 1044 may be moved through the lumen while recordingposition data thereof. This allows for aligning an image representing alocation of said location sensor with an image of said three-dimensionalmodel based on said recorded position data and an assumption that saidprobe remains located in non-tissue space. When moving the locationsensor 1044 within a branched structure, data is recorded pertaining tolocations of the location sensor 1044 while it is moving through saidbranched structure. Then a shape resulting from said data is compared toan interior geometry of passages of said three-dimensional model of saidbranched structure generated from the CT data. This provides fordetermining a location correlation between said shape and saidthree-dimensional model based on said comparison.

Registration using the technique of the present disclosure isaccomplished by placing a location sensor 1044 into the airways andcontinually recording its position. This continues until there is enoughdata for a shape-matching algorithm to determine that the “painted”shape can only fit within the 3D CT volume in one place and orientation.Another way to accomplish initial registration is to simply navigate theprobe down a plurality of various airways, preferably selected in bothlungs. As stated above, the more airways visited, the smaller theregistration error.

Yet a further procedure is described with reference to FIG. 15. In themethod of FIG. 15 the bronchoscope 1004 is inserted into the patient1000, as shown in FIG. 11. The locatable guide 1032 is extended beyondthe end of the sheath 1040, both of which extend approximately 10 mmpast the distal end of the bronchoscope 1004.

Once in place in the patient 1000, a screen 1100 will be displayed bythe software on the monitoring equipment 1006 (FIG. 11). The right imageis the actual bronchoscopic image 1102 generated by the bronchoscope1004. Initially there is no image displayed in the left image 1104, thiswill be a virtual bronchoscopy, as discussed above, generated from theCT image data, once registration is complete.

Starting with the locatable guide 1036, and specifically the sensorelement 1044 approximately 3-4 cm above the main carina, as viewedthrough the bronchoscope 1004, the bronchoscope is advanced into boththe right and left lungs to the fourth generation of the lung passages.By traversing these segments of the lungs, sufficient data is collectedas described above such that registration can be accomplished. Whenregistration is achieved, which may be indicated to the user byhighlighting the virtual bronchoscopy image 1104 in green, or some othervisual indicator, the registration can be checked. This is accomplishedby again directing the bronchoscope to image the main carina and both ofthe right upper lobe and left upper lobe carina. Visual comparison bythe user confirms that the registration is accurate. If needed, rotationof the visual bronchoscopy by the user can correct minor image issues.If the user is displeased with the results, or is unable to achieveregistration, perhaps due to a prior resection or treatment of thepatient's lungs, manual registration is always available for use, asdescribed above.

Now that the targets have been identified, the pathway planned, thebronchoscope 1004 including locatable guide 1032 inserted into thepatient 1000, and the virtual bronchoscopy image registered with theimage data of the bronchoscope 1004, the system is ready to navigate thelocation sensor 1044 to the target within the patient's lungs. Thecomputer 1024 provides a display similar to that shown in FIG. 10identifying the target 1017 and depicting the virtual bronchoscopy image1011. However, appearing in each of the images on the display is thepathway from the current location of the location sensor 1044 to thetarget 1017. This is the pathway that was established during the pathwayplanning phase discussed above. The pathway may be represented, forexample, by a colored line. Also appearing in each image is arepresentation of the distal tip of the locatable guide 1032 andlocation sensor 1044. By advancing the locatable guide 1032 andfollowing the pathway the medical professional is able to follow theidentified pathway to the target 1017. At times, as discussed above, thevirtual bronchoscopy image 1017 may not provide sufficient accuracy,particularly at the pleura boundaries of the lungs. In such instancesthe user can rely on the CT images 1005-1009 to provide greater details.Though shown with just three views in images 1005-1009, there are infact a wide variety of images that can be employed here, mostly derivedfrom the CT imaging data.

Although the position of the location sensor 1044 is measured in realtime, the target 1017 location is not. The target 1017 is generallyconsidered fixed relative to the patient's body position 1000 which ismonitored in real time by sensors 1020 (FIG. 12). However, navigationaccuracy may decrease as a result of cyclic chest movement resultingfrom breathing. Preferably, precautions are taken to reduce the effectsof this cyclic movement including reducing the respiration rate of thepatient. In addition this movement may be accounted for in the softwareby sampling the position sensors positions 1020 selectively so thatmeasurements are only made at an extreme of a cyclic motion. Theextremes of the motion of the patient's chest can readily be identifiedby the cyclic displacement of sensors 1020 during the breathing cycle.It may be preferred to use the maximum exhalation state for measurementssince this state typically remains steady for a relatively largerproportion of the breath cycle than the maximum inhalation state.Alternatively, measurements can be taken continuously, and the cyclicvariations eliminated or reduced by additional processing. Thisprocessing may include applying a low-frequency filter to themeasurements. Alternatively, an average of the measurements over a timeperiod of the cyclic motion may be calculated and used to assist inapproximating the location of the target. This is assisted by knowingwhether the CT data was derived with the patient in a fully inhaled orexhaled position, which can be used for comparison and greaterapproximation of positioning.

Once the locatable guide 1032 has successfully been navigated to thetarget 1017 location, the locatable guide 1032 is preferably removed,leaving sheath 1040 in place as a guide channel for bringing a tool tothe target location 1017. The medical tools may be biopsy tools that canbe used to sample the target 1017. These samples are retrieved and adetermination is made whether treatment of the target is necessary.Details of this system are included in U.S. Pat. No. 7,233,820, alreadyincorporated herein by reference.

A further use of the sheath 1040 following removal of the locatableguide 1032 is as a conduit for the placement of one or more markers(1300 FIG. 17) within the patient. These markers can be used for avariety of purposes including identifying tumors and lesions forfollow-up analysis and monitoring, to identify locations that biopsysampling has been undertaken, and to identify the boundaries or thecenter of a tumor or lesion for application of treatment. Other useswill be understood by those of skill in the art as falling within thescope of the present disclosure.

The placement of markers can be particularly useful in the context ofperforming a video assisted thoracoscopic surgery (VATS) lung procedure.VATS procedures performed on a patient 1000 of FIG. 16A involvesinserting a video scope 1200 (camera) and laparoscopic tools including aforceps 1202 and an ablation probe 1204 into the chest cavity of thepatient 1000 though one or more ports formed in the chest wall. Thevideo scope 1200 allows the surgeon to visualize the lung 1206 on amonitor 1208, as depicted in FIG. 16B. The ablation probe 1204 isinserted into the tissue of the lung 1206 and energized in order toablate the tissue of interest and treat the lung tissue as describedabove.

Though described here with respect to treatment of lung tissueembodiments of the present disclosure are equally applicable for use intreatment of other tissues. For example, it is contemplated that thesystems and methods of the present disclosure may be used to treat livertissue, kidney tissue, pancreatic tissue, gastrointestinal tissue,interstitial masses, and other portions of the body known to those ofskill in the art to be treatable via microwave ablation.

Returning to the treatment of lung tissue, lung lesions, especiallysmall ones or those located on closer to the pleura boundaries aredifficult for thoracic medical professionals to identify and treatvisually. To most clearly distinguish the tissue of interest, themedical professional should have either a tactile or a visible markerplaced near the tissue of interest to help target the tissue slated forremoval or ablation.

Accordingly to one embodiment of the present disclosure, using thesystem described above with reference to FIGS. 11 and 12, a medicalprofessional is able to navigate a sheath 1040 through the workingchannel of a bronchoscope 1004 by manipulating control handle 1038 andtherewith locatable guide 1032 to position a sensor 1044 proximal tissueof interest. This navigation of the lung must be performed while thelungs are inflated, or at least undergoing normal, albeit slowedrespiration by the patient. According to at least one embodiment, withthe sheath 1040 remaining in place, the locatable guide 1032 is removedfrom the sheath 1040, the medical professional is able to use the sheath1044 to deploy one or more markers to identify the location of interest.As noted, above, this may be in order to return to this location forfurther study, treatment, biopsy, etc., or this may be used to identifylocations for VATS procedures.

Though described herein with respect to a particular planning andnavigation systems, other pathway planning and navigation systems may beemployed without departing from the scope of the present disclosure. Forexample, the systems described in commonly assigned U.S. patentapplication Ser. Nos. 13/477,279; 13/477,291; 13/477,374; 13/477,395;13/477,406; and 13/477,417, the entire contents of which areincorporated herein by reference, as well as those systems described forexample is U.S. Pat. No. 7,876,942 currently assigned to Activiewes,LTD.

In order to perform VATS procedures, following placement of the markersthe lung 1206, or a portion of the lung 1206 is typically deflated.Deflation makes room for the video scope 1206 and other necessary tools(e.g., forceps 1202). Further, this deflation leads greater energyabsorption during microwave ablation because of the lower dielectricconstant and dissipation factor of air as compared to lung tissue,accordingly removal of the air increase the overall absorption ofmicrowave energy by the lung tissue, leading to higher tissuetemperatures. Additionally, deflation reduces the thermal cooling whichwould otherwise occur from respiration of the lung, further increasingthermal ablation effectiveness.

A variety of techniques for identification of the location of implantedmarkers can be employed including fluoroscopy, ultrasound, and otherimaging modalities. These are particularly useful when the marker isequipped with a radio-opaque portion, formed of, for example, gold. VATSprocedures in particular lend themselves to visual identification,particularly when performing treatment of tissues near the pleuraboundaries of the lungs. Some techniques to improve visualizationinvolve the injection of inks or dyes into the patient to identify thelocation of the marker. These techniques tend to be more of a clinicianbased ad hoc solution to visual identification.

As an initial matter visualizing of markers of any kind, especially in adiscolored and diseased lung tissue, can be very difficult. Further,traditional dyes and solutions tend to be spread too broadly foraccurate identification of the tissue to be identified, particularly ifthe marker is placed more than a few hours before the surgicalprocedure. Typically surgery must be undertaken within 72 hours of dyeinjection. Gold fiducial markers on the other hand are difficult if notimpossible to identify without some imaging modality, and sometimescurrently available fiducial markers tend to migrate over time, or evenas a result of a patient cough.

One embodiment of the present disclosure is directed to placement of amarker using the system described herein to promote visualidentification of the tissue of interest during VATS and so that thetissue can be percutaneously ablated using the microwave system of FIG.2A. FIG. 17 shows such a marker 1300. The marker 1300 of FIG. 17 is madeof made of a biocompatible material and includes an expanding materialsuch as an implant grade hydrogel. In its dehydrated state, depicted inFIG. 18 as the darker cylinder 1302, the marker 1300 is compatible withand fits within the inner diameter of a sheath 1040 of the catheterassembly 1030 of FIG. 12. For example, the diameter of the marker 1300in its dehydrated state may be approximately 2 mm.

One method of deployment is to use a push catheter (not shown) to forcethe marker 1300 through the sheath 1040. Markings on the push catheterenable the medical professional to know when the marker 1300 has beendeployed out the distal end of the sheath 1040. Placement of the marker1300 may be either into the airway directly or alternatively, into avoid created using a biopsy tool. The void may be in for example a tumoror mass and may allow for clear identification of the center of thetumor for ablation purposes.

The color of the dark cylinder 1302 is due to the expanding materialenclosed therein having absorbed an ink material, such as methelyneblue, indigo carmine, isosulfan blue, gentian violet, or others known tothose of skill in the art. In one alternative, rather than an ink aradio opaque fluid/gel may also be employed.

Once placed in the body, the expanding material, such as a hydrogel,absorbs water and begins to expand until achieving an expanded size1304. Similar technologies are currently employed for placing breastbiopsy markers. Over a short period of time the expanding materialswells which assists in securing the marker 1300 in place. According tothe present disclosure, in addition to the foregoing, while fluid isbeing absorbed into the hydrogel, the ink in the hydrogel can begin toleave the hydrogel via osmosis. However, because of the hydrogelmaterial the rate of osmosis of the ink is metered, such that migrationof the ink is greatly reduced as compared to direct injection of theinks as discussed above. One advantage of using ink is that it has theability to penetrate calcified lesions or surrounding parenchyma of thelung 1206 and to clearly identify its location to a surgeon when viewingthe lungs through a video scope 1200, as shown in FIG. 16B.

FIG. 18 depicts the effect of the implantation of a marker 1300 in alung 1206 according to the present disclosure. Specifically FIG. 18provides the image a medical professional might see when viewing lung1206 though a video scope 1200. The dime is placed in the image for sizecomparison purposes. This image is as one might see shortly(approximately 1-hour) after implantation, of marker 1300 near thepleura boundary of a lung 1206. FIG. 19 depicts the same marker 1300approximately 16 hours after implantation in the lung 1206 and while thelung 1206 is in a deflated state. As can be seen by the comparison theink 1305 in the marker 1300 clearly defines the location of the marker1300 on the lung 1206, but has not diffused to the point of marking toomuch of the lung 1206, and thus provides a good indication of thelocation of the marker 1300. Thus the tissue of interest can be readilyvisualized by a medical professional performing a VATS procedure, forexample to perform microwave ablation as disclosed herein. Further, as aresult of the use of the marker 1300, even a small area of interest canbe identified and a biopsy sample taken or surgical procedure undertakenand trauma to surrounding, otherwise healthy tissue can be minimized.Though shown above after 16 hours of implantation, it is contemplatedthat markers of the present disclosure can be implanted up to one weekprior to the procedure and still provide useable identification of thetissue of interest.

Another aspect of the marker of the present disclosure is that it mayoptionally contain a metallic or radio opaque marker within it. Metalsusable for such a configuration include titanium, gold, and others. Asshown in FIG. 20, the marker 1300 is depicted in its expanded state1304, but without ink 1305, encloses a metallic (radio opaque) marker1306. This metallic marker 1306 allows the position of the marker 1300to be determined using fluoroscopy or other imaging modalities, toassist the surgeon. In the embodiments disclosed herein, the expandablematerial is preferably biodegradable, thus over time, for example 4-6weeks the expandable material will degrade and be absorbed by the body.

Although embodiments have been described in detail with reference to theaccompanying drawings for the purpose of illustration and description,it is to be understood that the inventive processes and apparatus arenot to be construed as limited thereby. It will be apparent to those ofordinary skill in the art that various modifications to the foregoingembodiments may be made without departing from the scope of thedisclosure.

What is claimed is:
 1. A microwave probe assembly, comprising: a hubhaving a proximal end and a distal end and at least two ports; a hub capsized to be received in a distal end of the hub; an antenna transitionassembly sized to be received in the proximal end of the hub; a hubdivider sized to be received between the hub cap and the antennatransition assembly and forming a first and a second chamber; an innertubular member received within a lumen of the hub divider; and a metalcylinder located columinally within inner tubular member and promoting aseal between the hub divider and the inner tubular member separating thefirst and second chambers.
 2. The microwave probe assembly of claim 1,wherein the hub divider is formed of an elastomeric material.
 3. Themicrowave probe assembly of claim 1, wherein the hub divider creates awater tight seal separating the first chamber from the second chamber.4. The microwave probe assembly of claim 1, wherein the at least twoports comprises a first port and a second port.
 5. The microwave probeassembly of claim 4, wherein the first chamber is disposed in fluidcommunication with the first port and the second chamber is disposed influid communication with the second port.
 6. The microwave probeassembly of claim 1, further comprising an outer tubular member arrangedconcentrically around the inner tubular member.
 7. The microwave probeassembly of claim 6, further comprising a first lumen disposed betweenthe outer tubular member and the inner tubular member and a second lumendisposed between the inner tubular member and a feedline.
 8. Themicrowave probe assembly of claim 7, wherein the first lumen is disposedin fluid communication with the first port and the second lumen isdisposed in fluid communication with the second port.
 9. The microwaveprobe assembly of claim 7, wherein the inner tubular member includes afirst portion having a first outer diameter, a second portion having asecond outer diameter greater than the first outer diameter, and a neckportion disposed between the first portion and the second portion,wherein the second portion is received within the lumen of the hubdivider.